Electrochromism is a phenomenon in which a material exhibits a reversible electrochemically-mediated change in an optical property when placed in a different electronic state, typically by being subjected to a voltage change. The optical property is typically one or more of color, transmittance, absorbance, and reflectance. One well known EC material, for example, is tungsten oxide (WO3). Tungsten oxide is a cathodic EC material in which a coloration transition, transparent to blue, occurs by electrochemical reduction. While electrochromism was discovered in the 1960's, EC devices and apparatus and systems containing EC devices have not begun to realize their full commercial potential.
Electrochromic materials may be incorporated into, for example, windows. One drawback of conventional EC windows is that the power used, although small in amount, requires a hard wired connection to a power source of a building. This creates problems when builders are installing, for example, a large number of windows in an office building. Having to deal with hard wiring required for windows is just another impediment that a builder must deal with in the long list of items necessary to build a modern structure. Also, although EC windows offer an elegant solution in the management of heat zones in a modern building, for example, when controlled by an automated heat and/or energy management system, EC windows that require hard wired power sources create impediments to integration into automated energy management systems. Thus the additional installation costs and risks associated with wires will slow down the adoption of EC windows in new construction and may prevent retrofit applications in many cases because retrofit requires additional installation of wiring infrastructure for the new EC windows.